The present invention relates to coin- or token-operated tennis nets in general, and more particularly to a tennis net which is raised to its playing position upon insertion of a coin token or card in a control box, and which is automatically lowered after a predetermined period of playing time.
Sports, such as tennis or volleyball for example, make use of a net which is stretched between two support posts on a court. Commercial utilization of such courts requires that an attendant be present to collect fees according to the duration of use of the courts by players.
Such sports, tennis or volleyball, require that the net be stretched at a predetermined regulation height, and if the net is too high or too low relative to the regulation height, normal play is prevented. More particularly, if the net is completely lowered, there is no possibility of a normal play taking place.
Devices have been proposed in the past for automatically raising a playing net, such as used in tennis or volleyball for example, upon insertion of a coin or token in an appropriate controlling component. After a predetermined period of time, the net is automatically lowered. By way of such a device, money for the use of the courts may be collected without the presence of an attendant for collecting the fees and timing of the use of the courts.
Applicant is aware of the existence of the following prior art:
U.S. Pat. No. 3,995,854 disclosing telescopic support posts for a net, which are extended by a lift mechanism upon the insertion of coins in a controlling component. The posts are automatically lowered under the control of a timing mechanism at the end of a predetermined time period.
U.S. Pat. No. 1,998,454 also disclosing a mechanism for raising and lowering a net. The mechanism takes the form of a pair of electric motor-driven screwjacks disposed each in one of the posts and supporting the net or, in the alternative, consists of a hydraulic jack in each post for raising and lowering the net.
U.S. Pat. No. 3,645,370 which discloses a hydraulically operated ram which is connected to the support cord of a net such that the net is raised when the ram is extended and lowered when the ram is retracted. The ram is extended by a manually operable pump, and a coin-operated mechanism sets a timing device which opens a valve after a predetermined time period, thus permitting the ram to retract under the weight of the net.
French Patent Publication No. 2,424,592 disclosing a net raising and lowering mechanism of the screwjack type driven by an electric motor controlled by the insertion of a coin.
German Patent Publication No. 2,912,528 disclosing a winch around which a net support cord is wound, and a manually-operated lever and ratchet mechanism for driving the winch, such that the net may be manually raised. An electromagnetic clutch is mounted between the ratchet mechanism and the winch, and the energization of the electromagnets after a predetermined period of time releases the winch, thus allowing drop of the net by gravity.
Such devices, as presently known, of the prior art present the disadvantages of usng complex mechanisms, electrical or hydraulic, of achieving raising and lowering of a net by way of telescoping posts, by way of screwjacks requiring the posts to be slotted or, according to the disclosure of the German patent publication No. 3,645,370, requiring manual raising of the net. All known devices of the prior art require that conventional net support posts be replaced by posts specifically designed for the purpose, or be substantially modified to accept the net raising and lowering mechanism.